"She believed all were equal and never judged anyone by their colour, position or wealth," Lisa says.

"I found the exposure to [racism] infuriating but Sarah would calm me and say, 'Bub, it is better to change minds through people realising I'm a decent human and getting to know me than by carrying on'.

"She felt deeply and passionately about racism and a fair go for her family and community who had seen so much disadvantage."

Fighting for life and love

By the end of 2014, Sarah was feeling confident about her health and life with her new baby and loving partner.

"My life, my loves, my family, my soulmate, my world, this year didn't make us weaker, it made us stronger in so many ways," she wrote in the journal she left for Lisa to read.

"I wish you happiness, laughter and good health, not just for 2015 but for a lifetime. Just love, life's too short not to, plus it's free."

Image At the time Sarah visited Uluru with Yarrul and her partner Lisa she was struggling to swallow as a result of her treatment.(Lisa Saffery)

But marriage remained "off the table" for the couple — and not by choice.

By 2015, Sarah was told she was tumour-free but having cancer and a baby ignited a sense of urgency around the issue.

Lisa says Sarah did what she felt was the most powerful thing she could — she penned a letter to their local MP Michael McCormack, now Deputy Prime Minister, begging him to allow them to marry.

In the letter, published in the local newspaper, Sarah outlined her diagnosis, describing her subsequent major surgeries and chemotherapy, all endured with Lisa's unwavering support.

"Ten months ago my main concern was to live, to be alive, to watch our children grow and to grow old with my partner and I can assure you, I am doing just that," she wrote.

"I'm asking/begging either of two things: that you change your view on same-sex marriage and join a force that will no doubt change history … or if something were to happen to me, explain to my children the exact reasons why you believe their mums weren't allowed to marry."